1. Technical Field
The present invention relates to a diagnostic agent useful for diagnostic imaging for angiopathic diseases such as dissecting aortic aneurysm (also called aortic dissection) and angiitis, and to a kit for diagnosis.
2. Description of the Related Art
The onset mechanism of dissecting aortic aneurysm includes partial breakage of intima of an aorta, flow of blood from a formed hiatus to media to cause dissection of a vascular wall, and necrosis of vascular smooth muscle cells. Grave cases bring strong pectralgia and a high fatality rate. As onset factors for these diseases, there are indicated hypertension, as well as degeneration and fragility-increase of media caused by arterial sclerosis and cystic medial necrosis.
Meanwhile, angiitis is caused by a factor such as collagen disease, and a lesion thereof often extends blood vessels of the whole body accompanied by necrosis of vascular smooth muscle cells and induces a grave fatal complication such as DIC (disseminated intravascular coagulation), thrombosis, or embolism.
Thus, many angiopathic diseases accompanied by necrosis of vascular smooth muscle cells, such as dissecting aortic aneurysm or angiitis, are grave diseases and therefore a speedy and accurate diagnosis is needed for effective medical treatment and prevention of complications.
Conventionally, these angiopathic diseases have been diagnosed only through morphological diagnosis conducted by diagnostic imaging or on the basis of abnormal values of general biological blood tests attributed to a primary disease, since there exist no specific test methods for these diseases. Thus, diagnosis of angiopathic diseases has confronted great difficulties.
Among these diagnosis methods, there are utilized echography, CT (X-ray computer tomography), DSA (digital subtraction angiography), MRI (magnetic resonance imaging), and aortography used as a method for diagnosing dissecting aortic aneurysm similar to that for diagnosing other heart diseases. Of these, DSA and aortagraphy are dangerous test methods in an acute stage of the diseases due to considerable invasiveness. In contrast, diagnostic imaging including echography, CT, and MRI, although less dangerous even in an acute stage, generally yields a morphological diagnosis, which is not able to distinguish between an old inveterate lesion and a new lesion in an acute stage. Thus, the above diagnostic imaging is not able to specifically diagnose a pathological region in an acute stage at which vascular smooth muscle cells are being damaged.
Meanwhile, a method for diagnosing angiitis through conventional diagnostic imaging is more difficult than that for diagnosing dissecting aortic aneurysm, since anglitis itself is a disease accompanied by no characteristic morphological changes.
Therefore, an object of the present invention is to develop a tracer preparation to enable accurate diagnostic imaging for a region affected by these diseases by binding specifically to vascular smooth muscle cells damaged at an acute stage of dissecting aortic aneurysm or angiitis.